A liquid crystal display device has been used in many fields, such as a television, computer display and electronic notebook, and particular attention has been paid to liquid crystal display devices being lightweight and having a small thickness and low power dissipation.
In a liquid crystal projector, for example, white color light from a light source is spectrally divided by a dichroic mirror, etc., into three primary colors, red, green and blue. These light color-components are incident on three independent liquid crystal devices to display a red, a green and a blue image, and these display images are again optically combined to project a resultant image on a transmission or a reflection screen for color display.
A liquid crystal display device for a liquid crystal projector has to meet the requirements that an incident optical system and projection optical system be made small without increasing their size. It is also required that, because the display image on the liquid crystal display device is projected in an enlarged form onto a screen, the display device be made compact and the display pixels be made at a fine pitch.
Attempts have been made, in such a liquid crystal display device, to form a display panel constructed of a plurality of display pixels, as well as a drive circuit section driving these display pixels, as one unit over a substrate to eliminate cumbersome interconnection between the display panel and the drive circuit section.
The drive circuit section of the above-mentioned display device is comprised mainly of a shift register array where normally a plurality of shift registers is connected in one array. This is disclosed, for example, in SID 93 DIGEST p383-p386 "A 1.9-in. 1.5-Mpixel Driver Fully-Integrated Poly-Si TFT-LCD for HDTV Projection".
However, since the shift register array is a type that transfers a signal sequentially through these shift registers, if there are any defects, such as shorting, in part of the shift register array, then all the downstream shift registers fail.
In order to eliminate this drawback, for example, Jpn. Pat. Appln. KOKAI Publication No. 62-271569 discloses, using, as a drive circuit section of the display device, a driver circuit comprised of one pair of decoders instead of shift registers for outputting sequential pulses on the basis of a binary count value for counting a clock pulse and its inverted replica.
If the drive circuit section is comprised mainly of decoders, when there is any break or short in part of the interconnection, an output is not obtained at an area corresponding to any defect area, but it is possible to secure adequate reliability by, for example, providing one pair of decoders as a redundant unit in the drive circuit.
In the arrangement disclosed in Jpn. Pat. Appln. KOKAI Publication No. 62-271569, however, the decoder has a plurality of logic circuit sections each corresponding to one scanning line or one signal line and, hence, not only the number of connection lines for transmitting numeral signals but also the number of logic circuit sections is increased as the definition of the display device increases. Cconversely, this causes decreases the manufacturing yield. Further, since the respective logic circuit sections are arranged to correspond to one scanning line-or-one signal line each, no adequate measure can be taken against high speed operation requirements resulting from the high definition of the display device.
A method is known by which, in the case where the number of effective scanning lines of a video signal, for example, is less than the number of horizontal pixel lines, the display panel's horizontal pixel lines remaining as ones not corresponding to the effective scanning lines of the video signal are scanned during a vertical blanking period, etc., to display a black blank display. In the above-mentioned arrangement, it is difficult to scan all the remaining horizontal pixel lines in a very brief period of time. It is, therefore, not possible to expect any positive black display.
The object of the present invention is to provide a display device to solve the above-mentioned technical task, according to which it is possible to markedly reduce any operation error.
Another object of the present invention is to provide a display device and drive method which can obtain a better display image even when the number of horizontal pixel lines of the display panel and number of effective scanning lines, or the of the display pixels in one horizontal pixel line and number of video data of the video signal, differ.